I could not disagree more. The show's decision to ground everything in the "real world" changed Dexter from an avenging angel to a person with emotional/psychological problems that are actually pretty far removed from reality.

The conceit of a "dark passenger" that identified evil, rather than just Dexter's subjective decisions or evidence-based judgements brought Dexter into a certainty that is missing in the show, and ultimately planted the seeds of doom for the series. Once Dexter is ambivalent it's over.

IMO